1 /*
2  * Written by Doug Lea with assistance from members of JCP JSR-166
3  * Expert Group and released to the public domain, as explained at
4  * http://creativecommons.org/publicdomain/zero/1.0/
5  * Other contributors include Andrew Wright, Jeffrey Hayes,
6  * Pat Fisher, Mike Judd.
7  */
8 
9 package jsr166;
10 
11 import java.util.ArrayList;
12 import java.util.Arrays;
13 import java.util.Collection;
14 import java.util.Collections;
15 import java.util.Enumeration;
16 import java.util.Iterator;
17 import java.util.Map;
18 import java.util.Random;
19 import java.util.Set;
20 import java.util.concurrent.ConcurrentHashMap;
21 
22 import junit.framework.Test;
23 import junit.framework.TestSuite;
24 
25 public class ConcurrentHashMapTest extends JSR166TestCase {
26     // android-note: Removed because the CTS runner does a bad job of
27     // retrying tests that have suite() declarations.
28     //
29     // public static void main(String[] args) {
30     //     main(suite(), args);
31     // }
32     // public static Test suite() {
33     //     return new TestSuite(ConcurrentHashMapTest.class);
34     // }
35 
36     /**
37      * Returns a new map from Integers 1-5 to Strings "A"-"E".
38      */
map5()39     private static ConcurrentHashMap<Integer, String> map5() {
40         ConcurrentHashMap map = new ConcurrentHashMap<Integer, String>(5);
41         assertTrue(map.isEmpty());
42         map.put(one, "A");
43         map.put(two, "B");
44         map.put(three, "C");
45         map.put(four, "D");
46         map.put(five, "E");
47         assertFalse(map.isEmpty());
48         assertEquals(5, map.size());
49         return map;
50     }
51 
52     /** Re-implement Integer.compare for old java versions */
compare(int x, int y)53     static int compare(int x, int y) {
54         return (x < y) ? -1 : (x > y) ? 1 : 0;
55     }
56 
57     // classes for testing Comparable fallbacks
58     static class BI implements Comparable<BI> {
59         private final int value;
BI(int value)60         BI(int value) { this.value = value; }
compareTo(BI other)61         public int compareTo(BI other) {
62             return compare(value, other.value);
63         }
equals(Object x)64         public boolean equals(Object x) {
65             return (x instanceof BI) && ((BI)x).value == value;
66         }
hashCode()67         public int hashCode() { return 42; }
68     }
CI(int value)69     static class CI extends BI { CI(int value) { super(value); } }
DI(int value)70     static class DI extends BI { DI(int value) { super(value); } }
71 
72     static class BS implements Comparable<BS> {
73         private final String value;
BS(String value)74         BS(String value) { this.value = value; }
compareTo(BS other)75         public int compareTo(BS other) {
76             return value.compareTo(other.value);
77         }
equals(Object x)78         public boolean equals(Object x) {
79             return (x instanceof BS) && value.equals(((BS)x).value);
80         }
hashCode()81         public int hashCode() { return 42; }
82     }
83 
84     static class LexicographicList<E extends Comparable<E>> extends ArrayList<E>
85         implements Comparable<LexicographicList<E>> {
LexicographicList(Collection<E> c)86         LexicographicList(Collection<E> c) { super(c); }
LexicographicList(E e)87         LexicographicList(E e) { super(Collections.singleton(e)); }
compareTo(LexicographicList<E> other)88         public int compareTo(LexicographicList<E> other) {
89             int common = Math.min(size(), other.size());
90             int r = 0;
91             for (int i = 0; i < common; i++) {
92                 if ((r = get(i).compareTo(other.get(i))) != 0)
93                     break;
94             }
95             if (r == 0)
96                 r = compare(size(), other.size());
97             return r;
98         }
99         private static final long serialVersionUID = 0;
100     }
101 
102     static class CollidingObject {
103         final String value;
CollidingObject(final String value)104         CollidingObject(final String value) { this.value = value; }
hashCode()105         public int hashCode() { return this.value.hashCode() & 1; }
equals(final Object obj)106         public boolean equals(final Object obj) {
107             return (obj instanceof CollidingObject) && ((CollidingObject)obj).value.equals(value);
108         }
109     }
110 
111     static class ComparableCollidingObject extends CollidingObject implements Comparable<ComparableCollidingObject> {
ComparableCollidingObject(final String value)112         ComparableCollidingObject(final String value) { super(value); }
compareTo(final ComparableCollidingObject o)113         public int compareTo(final ComparableCollidingObject o) {
114             return value.compareTo(o.value);
115         }
116     }
117 
118     /**
119      * Inserted elements that are subclasses of the same Comparable
120      * class are found.
121      */
testComparableFamily()122     public void testComparableFamily() {
123         int size = 500;         // makes measured test run time -> 60ms
124         ConcurrentHashMap<BI, Boolean> m =
125             new ConcurrentHashMap<BI, Boolean>();
126         for (int i = 0; i < size; i++) {
127             assertTrue(m.put(new CI(i), true) == null);
128         }
129         for (int i = 0; i < size; i++) {
130             assertTrue(m.containsKey(new CI(i)));
131             assertTrue(m.containsKey(new DI(i)));
132         }
133     }
134 
135     /**
136      * Elements of classes with erased generic type parameters based
137      * on Comparable can be inserted and found.
138      */
testGenericComparable()139     public void testGenericComparable() {
140         int size = 120;         // makes measured test run time -> 60ms
141         ConcurrentHashMap<Object, Boolean> m =
142             new ConcurrentHashMap<Object, Boolean>();
143         for (int i = 0; i < size; i++) {
144             BI bi = new BI(i);
145             BS bs = new BS(String.valueOf(i));
146             LexicographicList<BI> bis = new LexicographicList<BI>(bi);
147             LexicographicList<BS> bss = new LexicographicList<BS>(bs);
148             assertTrue(m.putIfAbsent(bis, true) == null);
149             assertTrue(m.containsKey(bis));
150             if (m.putIfAbsent(bss, true) == null)
151                 assertTrue(m.containsKey(bss));
152             assertTrue(m.containsKey(bis));
153         }
154         for (int i = 0; i < size; i++) {
155             assertTrue(m.containsKey(Collections.singletonList(new BI(i))));
156         }
157     }
158 
159     /**
160      * Elements of non-comparable classes equal to those of classes
161      * with erased generic type parameters based on Comparable can be
162      * inserted and found.
163      */
testGenericComparable2()164     public void testGenericComparable2() {
165         int size = 500;         // makes measured test run time -> 60ms
166         ConcurrentHashMap<Object, Boolean> m =
167             new ConcurrentHashMap<Object, Boolean>();
168         for (int i = 0; i < size; i++) {
169             m.put(Collections.singletonList(new BI(i)), true);
170         }
171 
172         for (int i = 0; i < size; i++) {
173             LexicographicList<BI> bis = new LexicographicList<BI>(new BI(i));
174             assertTrue(m.containsKey(bis));
175         }
176     }
177 
178     /**
179      * Mixtures of instances of comparable and non-comparable classes
180      * can be inserted and found.
181      */
testMixedComparable()182     public void testMixedComparable() {
183         int size = 1200;        // makes measured test run time -> 35ms
184         ConcurrentHashMap<Object, Object> map =
185             new ConcurrentHashMap<Object, Object>();
186         Random rng = new Random();
187         for (int i = 0; i < size; i++) {
188             Object x;
189             switch (rng.nextInt(4)) {
190             case 0:
191                 x = new Object();
192                 break;
193             case 1:
194                 x = new CollidingObject(Integer.toString(i));
195                 break;
196             default:
197                 x = new ComparableCollidingObject(Integer.toString(i));
198             }
199             assertNull(map.put(x, x));
200         }
201         int count = 0;
202         for (Object k : map.keySet()) {
203             assertEquals(map.get(k), k);
204             ++count;
205         }
206         assertEquals(count, size);
207         assertEquals(map.size(), size);
208         for (Object k : map.keySet()) {
209             assertEquals(map.put(k, k), k);
210         }
211     }
212 
213     /**
214      * clear removes all pairs
215      */
testClear()216     public void testClear() {
217         ConcurrentHashMap map = map5();
218         map.clear();
219         assertEquals(0, map.size());
220     }
221 
222     /**
223      * Maps with same contents are equal
224      */
testEquals()225     public void testEquals() {
226         ConcurrentHashMap map1 = map5();
227         ConcurrentHashMap map2 = map5();
228         assertEquals(map1, map2);
229         assertEquals(map2, map1);
230         map1.clear();
231         assertFalse(map1.equals(map2));
232         assertFalse(map2.equals(map1));
233     }
234 
235     /**
236      * hashCode() equals sum of each key.hashCode ^ value.hashCode
237      */
testHashCode()238     public void testHashCode() {
239         ConcurrentHashMap<Integer,String> map = map5();
240         int sum = 0;
241         for (Map.Entry<Integer,String> e : map.entrySet())
242             sum += e.getKey().hashCode() ^ e.getValue().hashCode();
243         assertEquals(sum, map.hashCode());
244     }
245 
246     /**
247      * contains returns true for contained value
248      */
testContains()249     public void testContains() {
250         ConcurrentHashMap map = map5();
251         assertTrue(map.contains("A"));
252         assertFalse(map.contains("Z"));
253     }
254 
255     /**
256      * containsKey returns true for contained key
257      */
testContainsKey()258     public void testContainsKey() {
259         ConcurrentHashMap map = map5();
260         assertTrue(map.containsKey(one));
261         assertFalse(map.containsKey(zero));
262     }
263 
264     /**
265      * containsValue returns true for held values
266      */
testContainsValue()267     public void testContainsValue() {
268         ConcurrentHashMap map = map5();
269         assertTrue(map.containsValue("A"));
270         assertFalse(map.containsValue("Z"));
271     }
272 
273     /**
274      * enumeration returns an enumeration containing the correct
275      * elements
276      */
testEnumeration()277     public void testEnumeration() {
278         ConcurrentHashMap map = map5();
279         Enumeration e = map.elements();
280         int count = 0;
281         while (e.hasMoreElements()) {
282             count++;
283             e.nextElement();
284         }
285         assertEquals(5, count);
286     }
287 
288     /**
289      * get returns the correct element at the given key,
290      * or null if not present
291      */
testGet()292     public void testGet() {
293         ConcurrentHashMap map = map5();
294         assertEquals("A", (String)map.get(one));
295         ConcurrentHashMap empty = new ConcurrentHashMap();
296         assertNull(map.get("anything"));
297         assertNull(empty.get("anything"));
298     }
299 
300     /**
301      * isEmpty is true of empty map and false for non-empty
302      */
testIsEmpty()303     public void testIsEmpty() {
304         ConcurrentHashMap empty = new ConcurrentHashMap();
305         ConcurrentHashMap map = map5();
306         assertTrue(empty.isEmpty());
307         assertFalse(map.isEmpty());
308     }
309 
310     /**
311      * keys returns an enumeration containing all the keys from the map
312      */
testKeys()313     public void testKeys() {
314         ConcurrentHashMap map = map5();
315         Enumeration e = map.keys();
316         int count = 0;
317         while (e.hasMoreElements()) {
318             count++;
319             e.nextElement();
320         }
321         assertEquals(5, count);
322     }
323 
324     /**
325      * keySet returns a Set containing all the keys
326      */
testKeySet()327     public void testKeySet() {
328         ConcurrentHashMap map = map5();
329         Set s = map.keySet();
330         assertEquals(5, s.size());
331         assertTrue(s.contains(one));
332         assertTrue(s.contains(two));
333         assertTrue(s.contains(three));
334         assertTrue(s.contains(four));
335         assertTrue(s.contains(five));
336     }
337 
338     /**
339      * keySet.toArray returns contains all keys
340      */
testKeySetToArray()341     public void testKeySetToArray() {
342         ConcurrentHashMap map = map5();
343         Set s = map.keySet();
344         Object[] ar = s.toArray();
345         assertTrue(s.containsAll(Arrays.asList(ar)));
346         assertEquals(5, ar.length);
347         ar[0] = m10;
348         assertFalse(s.containsAll(Arrays.asList(ar)));
349     }
350 
351     /**
352      * Values.toArray contains all values
353      */
testValuesToArray()354     public void testValuesToArray() {
355         ConcurrentHashMap map = map5();
356         Collection v = map.values();
357         Object[] ar = v.toArray();
358         ArrayList s = new ArrayList(Arrays.asList(ar));
359         assertEquals(5, ar.length);
360         assertTrue(s.contains("A"));
361         assertTrue(s.contains("B"));
362         assertTrue(s.contains("C"));
363         assertTrue(s.contains("D"));
364         assertTrue(s.contains("E"));
365     }
366 
367     /**
368      * entrySet.toArray contains all entries
369      */
testEntrySetToArray()370     public void testEntrySetToArray() {
371         ConcurrentHashMap map = map5();
372         Set s = map.entrySet();
373         Object[] ar = s.toArray();
374         assertEquals(5, ar.length);
375         for (int i = 0; i < 5; ++i) {
376             assertTrue(map.containsKey(((Map.Entry)(ar[i])).getKey()));
377             assertTrue(map.containsValue(((Map.Entry)(ar[i])).getValue()));
378         }
379     }
380 
381     /**
382      * values collection contains all values
383      */
testValues()384     public void testValues() {
385         ConcurrentHashMap map = map5();
386         Collection s = map.values();
387         assertEquals(5, s.size());
388         assertTrue(s.contains("A"));
389         assertTrue(s.contains("B"));
390         assertTrue(s.contains("C"));
391         assertTrue(s.contains("D"));
392         assertTrue(s.contains("E"));
393     }
394 
395     /**
396      * entrySet contains all pairs
397      */
testEntrySet()398     public void testEntrySet() {
399         ConcurrentHashMap map = map5();
400         Set s = map.entrySet();
401         assertEquals(5, s.size());
402         Iterator it = s.iterator();
403         while (it.hasNext()) {
404             Map.Entry e = (Map.Entry) it.next();
405             assertTrue(
406                        (e.getKey().equals(one) && e.getValue().equals("A")) ||
407                        (e.getKey().equals(two) && e.getValue().equals("B")) ||
408                        (e.getKey().equals(three) && e.getValue().equals("C")) ||
409                        (e.getKey().equals(four) && e.getValue().equals("D")) ||
410                        (e.getKey().equals(five) && e.getValue().equals("E")));
411         }
412     }
413 
414     /**
415      * putAll adds all key-value pairs from the given map
416      */
testPutAll()417     public void testPutAll() {
418         ConcurrentHashMap empty = new ConcurrentHashMap();
419         ConcurrentHashMap map = map5();
420         empty.putAll(map);
421         assertEquals(5, empty.size());
422         assertTrue(empty.containsKey(one));
423         assertTrue(empty.containsKey(two));
424         assertTrue(empty.containsKey(three));
425         assertTrue(empty.containsKey(four));
426         assertTrue(empty.containsKey(five));
427     }
428 
429     /**
430      * putIfAbsent works when the given key is not present
431      */
testPutIfAbsent()432     public void testPutIfAbsent() {
433         ConcurrentHashMap map = map5();
434         map.putIfAbsent(six, "Z");
435         assertTrue(map.containsKey(six));
436     }
437 
438     /**
439      * putIfAbsent does not add the pair if the key is already present
440      */
testPutIfAbsent2()441     public void testPutIfAbsent2() {
442         ConcurrentHashMap map = map5();
443         assertEquals("A", map.putIfAbsent(one, "Z"));
444     }
445 
446     /**
447      * replace fails when the given key is not present
448      */
testReplace()449     public void testReplace() {
450         ConcurrentHashMap map = map5();
451         assertNull(map.replace(six, "Z"));
452         assertFalse(map.containsKey(six));
453     }
454 
455     /**
456      * replace succeeds if the key is already present
457      */
testReplace2()458     public void testReplace2() {
459         ConcurrentHashMap map = map5();
460         assertNotNull(map.replace(one, "Z"));
461         assertEquals("Z", map.get(one));
462     }
463 
464     /**
465      * replace value fails when the given key not mapped to expected value
466      */
testReplaceValue()467     public void testReplaceValue() {
468         ConcurrentHashMap map = map5();
469         assertEquals("A", map.get(one));
470         assertFalse(map.replace(one, "Z", "Z"));
471         assertEquals("A", map.get(one));
472     }
473 
474     /**
475      * replace value succeeds when the given key mapped to expected value
476      */
testReplaceValue2()477     public void testReplaceValue2() {
478         ConcurrentHashMap map = map5();
479         assertEquals("A", map.get(one));
480         assertTrue(map.replace(one, "A", "Z"));
481         assertEquals("Z", map.get(one));
482     }
483 
484     /**
485      * remove removes the correct key-value pair from the map
486      */
testRemove()487     public void testRemove() {
488         ConcurrentHashMap map = map5();
489         map.remove(five);
490         assertEquals(4, map.size());
491         assertFalse(map.containsKey(five));
492     }
493 
494     /**
495      * remove(key,value) removes only if pair present
496      */
testRemove2()497     public void testRemove2() {
498         ConcurrentHashMap map = map5();
499         map.remove(five, "E");
500         assertEquals(4, map.size());
501         assertFalse(map.containsKey(five));
502         map.remove(four, "A");
503         assertEquals(4, map.size());
504         assertTrue(map.containsKey(four));
505     }
506 
507     /**
508      * size returns the correct values
509      */
testSize()510     public void testSize() {
511         ConcurrentHashMap map = map5();
512         ConcurrentHashMap empty = new ConcurrentHashMap();
513         assertEquals(0, empty.size());
514         assertEquals(5, map.size());
515     }
516 
517     /**
518      * toString contains toString of elements
519      */
testToString()520     public void testToString() {
521         ConcurrentHashMap map = map5();
522         String s = map.toString();
523         for (int i = 1; i <= 5; ++i) {
524             assertTrue(s.contains(String.valueOf(i)));
525         }
526     }
527 
528     // Exception tests
529 
530     /**
531      * Cannot create with only negative capacity
532      */
testConstructor1()533     public void testConstructor1() {
534         try {
535             new ConcurrentHashMap(-1);
536             shouldThrow();
537         } catch (IllegalArgumentException success) {}
538     }
539 
540     /**
541      * Constructor (initialCapacity, loadFactor) throws
542      * IllegalArgumentException if either argument is negative
543      */
testConstructor2()544     public void testConstructor2() {
545         try {
546             new ConcurrentHashMap(-1, .75f);
547             shouldThrow();
548         } catch (IllegalArgumentException success) {}
549 
550         try {
551             new ConcurrentHashMap(16, -1);
552             shouldThrow();
553         } catch (IllegalArgumentException success) {}
554     }
555 
556     /**
557      * Constructor (initialCapacity, loadFactor, concurrencyLevel)
558      * throws IllegalArgumentException if any argument is negative
559      */
testConstructor3()560     public void testConstructor3() {
561         try {
562             new ConcurrentHashMap(-1, .75f, 1);
563             shouldThrow();
564         } catch (IllegalArgumentException success) {}
565 
566         try {
567             new ConcurrentHashMap(16, -1, 1);
568             shouldThrow();
569         } catch (IllegalArgumentException success) {}
570 
571         try {
572             new ConcurrentHashMap(16, .75f, -1);
573             shouldThrow();
574         } catch (IllegalArgumentException success) {}
575     }
576 
577     /**
578      * ConcurrentHashMap(map) throws NullPointerException if the given
579      * map is null
580      */
testConstructor4()581     public void testConstructor4() {
582         try {
583             new ConcurrentHashMap(null);
584             shouldThrow();
585         } catch (NullPointerException success) {}
586     }
587 
588     /**
589      * ConcurrentHashMap(map) creates a new map with the same mappings
590      * as the given map
591      */
testConstructor5()592     public void testConstructor5() {
593         ConcurrentHashMap map1 = map5();
594         ConcurrentHashMap map2 = new ConcurrentHashMap(map5());
595         assertTrue(map2.equals(map1));
596         map2.put(one, "F");
597         assertFalse(map2.equals(map1));
598     }
599 
600     /**
601      * get(null) throws NPE
602      */
testGet_NullPointerException()603     public void testGet_NullPointerException() {
604         ConcurrentHashMap c = new ConcurrentHashMap(5);
605         try {
606             c.get(null);
607             shouldThrow();
608         } catch (NullPointerException success) {}
609     }
610 
611     /**
612      * containsKey(null) throws NPE
613      */
testContainsKey_NullPointerException()614     public void testContainsKey_NullPointerException() {
615         ConcurrentHashMap c = new ConcurrentHashMap(5);
616         try {
617             c.containsKey(null);
618             shouldThrow();
619         } catch (NullPointerException success) {}
620     }
621 
622     /**
623      * containsValue(null) throws NPE
624      */
testContainsValue_NullPointerException()625     public void testContainsValue_NullPointerException() {
626         ConcurrentHashMap c = new ConcurrentHashMap(5);
627         try {
628             c.containsValue(null);
629             shouldThrow();
630         } catch (NullPointerException success) {}
631     }
632 
633     /**
634      * contains(null) throws NPE
635      */
testContains_NullPointerException()636     public void testContains_NullPointerException() {
637         ConcurrentHashMap c = new ConcurrentHashMap(5);
638         try {
639             c.contains(null);
640             shouldThrow();
641         } catch (NullPointerException success) {}
642     }
643 
644     /**
645      * put(null,x) throws NPE
646      */
testPut1_NullPointerException()647     public void testPut1_NullPointerException() {
648         ConcurrentHashMap c = new ConcurrentHashMap(5);
649         try {
650             c.put(null, "whatever");
651             shouldThrow();
652         } catch (NullPointerException success) {}
653     }
654 
655     /**
656      * put(x, null) throws NPE
657      */
testPut2_NullPointerException()658     public void testPut2_NullPointerException() {
659         ConcurrentHashMap c = new ConcurrentHashMap(5);
660         try {
661             c.put("whatever", null);
662             shouldThrow();
663         } catch (NullPointerException success) {}
664     }
665 
666     /**
667      * putIfAbsent(null, x) throws NPE
668      */
testPutIfAbsent1_NullPointerException()669     public void testPutIfAbsent1_NullPointerException() {
670         ConcurrentHashMap c = new ConcurrentHashMap(5);
671         try {
672             c.putIfAbsent(null, "whatever");
673             shouldThrow();
674         } catch (NullPointerException success) {}
675     }
676 
677     /**
678      * replace(null, x) throws NPE
679      */
testReplace_NullPointerException()680     public void testReplace_NullPointerException() {
681         ConcurrentHashMap c = new ConcurrentHashMap(5);
682         try {
683             c.replace(null, "whatever");
684             shouldThrow();
685         } catch (NullPointerException success) {}
686     }
687 
688     /**
689      * replace(null, x, y) throws NPE
690      */
testReplaceValue_NullPointerException()691     public void testReplaceValue_NullPointerException() {
692         ConcurrentHashMap c = new ConcurrentHashMap(5);
693         try {
694             c.replace(null, one, "whatever");
695             shouldThrow();
696         } catch (NullPointerException success) {}
697     }
698 
699     /**
700      * putIfAbsent(x, null) throws NPE
701      */
testPutIfAbsent2_NullPointerException()702     public void testPutIfAbsent2_NullPointerException() {
703         ConcurrentHashMap c = new ConcurrentHashMap(5);
704         try {
705             c.putIfAbsent("whatever", null);
706             shouldThrow();
707         } catch (NullPointerException success) {}
708     }
709 
710     /**
711      * replace(x, null) throws NPE
712      */
testReplace2_NullPointerException()713     public void testReplace2_NullPointerException() {
714         ConcurrentHashMap c = new ConcurrentHashMap(5);
715         try {
716             c.replace("whatever", null);
717             shouldThrow();
718         } catch (NullPointerException success) {}
719     }
720 
721     /**
722      * replace(x, null, y) throws NPE
723      */
testReplaceValue2_NullPointerException()724     public void testReplaceValue2_NullPointerException() {
725         ConcurrentHashMap c = new ConcurrentHashMap(5);
726         try {
727             c.replace("whatever", null, "A");
728             shouldThrow();
729         } catch (NullPointerException success) {}
730     }
731 
732     /**
733      * replace(x, y, null) throws NPE
734      */
testReplaceValue3_NullPointerException()735     public void testReplaceValue3_NullPointerException() {
736         ConcurrentHashMap c = new ConcurrentHashMap(5);
737         try {
738             c.replace("whatever", one, null);
739             shouldThrow();
740         } catch (NullPointerException success) {}
741     }
742 
743     /**
744      * remove(null) throws NPE
745      */
testRemove1_NullPointerException()746     public void testRemove1_NullPointerException() {
747         ConcurrentHashMap c = new ConcurrentHashMap(5);
748         c.put("sadsdf", "asdads");
749         try {
750             c.remove(null);
751             shouldThrow();
752         } catch (NullPointerException success) {}
753     }
754 
755     /**
756      * remove(null, x) throws NPE
757      */
testRemove2_NullPointerException()758     public void testRemove2_NullPointerException() {
759         ConcurrentHashMap c = new ConcurrentHashMap(5);
760         c.put("sadsdf", "asdads");
761         try {
762             c.remove(null, "whatever");
763             shouldThrow();
764         } catch (NullPointerException success) {}
765     }
766 
767     /**
768      * remove(x, null) returns false
769      */
testRemove3()770     public void testRemove3() {
771         ConcurrentHashMap c = new ConcurrentHashMap(5);
772         c.put("sadsdf", "asdads");
773         assertFalse(c.remove("sadsdf", null));
774     }
775 
776     /**
777      * A deserialized map equals original
778      */
testSerialization()779     public void testSerialization() throws Exception {
780         Map x = map5();
781         Map y = serialClone(x);
782 
783         assertNotSame(x, y);
784         assertEquals(x.size(), y.size());
785         assertEquals(x, y);
786         assertEquals(y, x);
787     }
788 
789     /**
790      * SetValue of an EntrySet entry sets value in the map.
791      */
testSetValueWriteThrough()792     public void testSetValueWriteThrough() {
793         // Adapted from a bug report by Eric Zoerner
794         ConcurrentHashMap map = new ConcurrentHashMap(2, 5.0f, 1);
795         assertTrue(map.isEmpty());
796         for (int i = 0; i < 20; i++)
797             map.put(new Integer(i), new Integer(i));
798         assertFalse(map.isEmpty());
799         Map.Entry entry1 = (Map.Entry)map.entrySet().iterator().next();
800         // Unless it happens to be first (in which case remainder of
801         // test is skipped), remove a possibly-colliding key from map
802         // which, under some implementations, may cause entry1 to be
803         // cloned in map
804         if (!entry1.getKey().equals(new Integer(16))) {
805             map.remove(new Integer(16));
806             entry1.setValue("XYZ");
807             assertTrue(map.containsValue("XYZ")); // fails if write-through broken
808         }
809     }
810 
811 }
812